[api-extractor] Fix self-package import resolution in TypeScript compiler (#5301)

When analyzing .d.ts files that import the package itself, TypeScript's module
resolution would redirect to source .ts files instead of analyzing the build
artifacts. This occurs because TypeScript tries to avoid analyzing build outputs
when outDir/declarationDir are set.

Fix by deleting outDir and declarationDir options from the compiler configuration,
as API Extractor only uses the compiler for analysis and doesn't emit files.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: finalchild <[email protected]>
Co-authored-by: Claude <[email protected]>

Author: finalchild

apps/api-extractor/src/api/CompilerState.ts

@@ -67,6 +67,15 @@ export class CompilerState {
       );
     }
 
+    // Delete outDir and declarationDir to prevent TypeScript from redirecting self-package
+    // imports to source files. When these options are set, TypeScript's module resolution
+    // tries to map output .d.ts files back to their source .ts files to avoid analyzing
+    // build outputs during compilation. However, API Extractor specifically wants to analyze
+    // the .d.ts build artifacts, not the source files. Since API Extractor doesn't emit any
+    // files, these options are unnecessary and interfere with correct module resolution.
+    delete commandLine.options.outDir;
+    delete commandLine.options.declarationDir;
+
     const inputFilePaths: string[] = commandLine.fileNames.concat(extractorConfig.mainEntryPointFilePath);
     if (options && options.additionalEntryPoints) {
       inputFilePaths.push(...options.additionalEntryPoints);

common/changes/@microsoft/api-extractor/fix-self-import-resolution_2025-08-07-10-22.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Fix self-package import resolution by removing outDir/declarationDir from compiler options",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}